西田 睦¹, 小井戸 一光², 市村 健², 廣川 直樹², 河合 有里子², 染谷 正則², 庄内 孝春², 中田 健生², 山 直也², 神山 直久³

Mutsumi NISHIDA¹, Kazumitsu KOITO², Takeshi ICHIMURA², Naoki HIROKAWA², Yuriko KAWAI², Masanori SOMEYA², Takaharu SYONAI², Kensei NAKATA², Naoya YAMA², Naohisa KAMIYAMA³

¹札幌医科大学大学院放射線治療診断学, ²札幌医科大学放射線科, ³東芝メディカルシステムズ

¹Radiation Oncology and Imaging and Diagnosis, Sapporo Medical University Graduate School of Medicine, ²Department of Radiology Sapporo Medical University, ³Toshiba Medical Systems

キーワード : contrast-enhanced ultrasonography, lymph nodes, metastasis, ultrasonography

目的：頸部リンパ節の悪性腫瘍転移診断に, 高周波プローブによる新しい造影エコー法Micro Flow Imaging (MFI)を試みた. 対象と方法：対象は, 頭頸部悪性腫瘍と診断され, 頸部リンパ節について超音波施行したのち, 手術がなされ, 病理組織学的に確定診断に至った3症例5結節とした. その内訳は, 左口蓋扁桃癌1例2結節, 舌癌1例3結節(2領域), 下歯肉癌1例1結節であった. 装置は東芝Aplio探触子は, 7-11 MHzのリニアプローブを用い, 造影剤はLevovist ^® 300 mg/ml 1 vを肘静脈から急速注入した. 造影モードはAdvanced Dynamic Flowを用い, acoustic powerは30-40%に設定し, MI値は約0.4前後とした. 造影手法は注入後10秒前後より40秒まで連続送信にて観察し, vascular phaseを得, 画像の重積処理(最大値保持演算)を行い, 新たな画像(MFI)を再構成した. 結果と考察：転移リンパ節ではリンパ節内に蛇行屈曲した血管構築が得られた. 一方, 転移陰性のリンパ節においてはリンパ門から流入し内部で樹枝状に分枝する血管構築が明瞭となった. 結語：MFIによりリンパ節内の微細血管構築が描出できた. この手法は頸部リンパ節の転移診断に有用である可能性が示唆された.

Purpose: To depict precise intranodal vessel structures of cervical lymph nodes by contrast-enhanced ultrasound (US) in patients with head and neck cancer. Patients and Methods: Three patients (lymph nodes in five regions) with head and neck cancer were studied by Micro Flow Imaging, a new contrast-enhanced ultrasound technique, using an Aplio unit (Model SSA-770 A, Toshiba MSC, Tokyo) with a 7-11 MHz linear transducer. Levovist^® (Tanabe/Schering AG, Berlin) was administered as a bolus infusion via the antecubital vein. Advanced Dynamic Flow Imaging at low acoustic power (30% to 50%) and a low mechanical index (approximately 0.4) was carried out for 40 to 60 seconds after the infusion. Sequential images acquired from 10 to 40 seconds after the infusion were accumulated, an operation that required maintaining the maximum brightness of each image, to construct the Micro-Flow Imaging. Results and Discussion: Intranodal vascularization was visualized more precisely in all cases by Micro Flow Imaging than by baseline contrast-enhanced ultrasound. The vessels appeared as intranodal tortuous flows in metastatic nodes; branching was normal in the hilar regions of reactive nodes. Conclusion: Micro Flow Imaging depicted intranodal vascularity more precisely than baseline contrast-enhanced ultrasound, thus suggesting that it might prove useful in differentiating metastatic and reactive lymph nodes.